Ocular diseases, such as degenerative cell proliferative diseases exemplified by age-related macular degeneration (ARMD), present a major health issue today. ARMD alone affects more than 1.75 million people in the U.S. It has been estimated that the number will increase to about 3 million by 2020 due to the rapid growing of the aging U.S. population. (see, e.g., Arch Ophthalmol, (2004) 122:564). ARMD is the principal cause of registered legal blindness and other visual disability among individuals over 60 years old in many parts of the world, including U.S., Western Europe, Australia, and Japan. (Ambati, et al., Surv. Ophthalmol., 48:257 May-June 2003; Zarbin, Arch. Ophthalmol., 2004, 122:598-614)
Clinical hallmarks of ARMD include drusen, hyperplasia or the retinal pigment epithelium (RPE), geographic atrophy, and choroidal neovascularization (CNV). Drusen are localized deposits of extracellular material found between the basement membrane of the RPE and Bruch's membrane. Drusen are characterized morphologically as either “soft”, with fuzzy, indistinct edges, or “hard”, with discrete, well-demarcated edges. Typically, drusen are clustered in the central macula, and exhibit a varied and complex morphology as determined by fundoscopic examination. It is well established in the art that the size, number and confluency of drusen are significant determinants for risk of developing ARMD. For a discussion of drusen as biomarkers of immune-mediated processes at the RPE-Bruch's membrane interface in ARMD, see Hageman et al. (2001) Retinal Eye Res. 20:705-732. In general, the precise pathogenic mechanisms that lead to ARMD are not well understood (for a review, see Zarbin, (2004), supra).
ARMD is generally characterized into two forms. The exudative or “wet” form of ARMD is characterized by CNV growth under the RPE and retina with subsequent hemorrhage, exudative retinal detachment, disciform scarring, and retinal atrophy, and can also be accompanied by serous or hemorrhagic pigment epithelial detachment. In the non-exudative or “dry” form of ARMD the accumulation of drusen is thought to cause atrophy of the macula, leading to vision loss. Wet ARMD accounts for about 75% of cases with several central vision loss. About 18% of people aged 65 to 74 years, and about 30% of people older than 74 years, have early ARMD, characterized by the presence of soft drusen or drusen with RPE degeneration or hyperpigmentation. (see, e.g., Zarbin (2004) supra)
There have been a number of reports assessing immune/inflammatory mechanisms in the formation of drusen in ARMD. One group has suggested that impaired macrophage recruitment may allow accumulation of C5a and IgG in the eye, which in turn induces vascular endothelial growth factor (VEGF) production by RPE, possibly mediating development of CNV, the primary cause of visual loss in the exudative or “wet” form of ARMD. Ambati et al. Nat Med. Nov. 9, 2003; (11):1390-7. Epub Oct. 19, 2003. Macrophages and foreign body giant calls have been reported near the Bruch's membrane where drusen is found (van der Schaft et al. Br J Ophthalmol. 1993 October; 77(10):657-61; Lopez et al. Am J Ophthalmol. 1991 112:647-56; Killlingsworth et al. Eye. 1990 4(Pt 4):613-21).
Others have hypothesized that macrophages and other inflammatory cells may be involved in CNV, which is part of the symptom in ARMD. For example, Oh et al. (Invest Ophthalmol Vis Sci 1999 40:1891-1898) suggested that IL-1β and TNF-α secreted by macrophages may promote, at least in part, angiogenesis in CNV membranes by stimulating VEGF production in RPE cells. Tsutsumi et al. (J Leukoc Biol. 2003 74:25-32) reported that mice that lack CCR2, the receptor for MCP-1, the number of infiltrating macrophage and the area of CNV were significantly reduced. Cousins et al. (Arch Ophthalmol. 2004 122:1013-8) evaluated the activation state of macrophage function in patients with age-related macular degeneration (AMD) by quantifying the production of the proinflammatory and angiogenic factor tumor necrosis factor alpha (TNF-α) and by correlating its expression with dry and wet AMD. This group reported that although wide variability in TNF-α expression by blood monocytes was observed among different patients, those patients with monocytes that expressed the greatest amount of TNF-α demonstrated higher prevalence of CNV.
Macrophages have also been reported to be associated with the Bruch's membrane in ARMD. Killingsworth, et al., Eye, 1990, 4: 613-621. Weller et al. (1991) Eur J Ophthalmol. 1:161-6 reported that posttraumatic proliferative retinopathy was apparently characterized by a severe initial inflammatory reaction as evidenced by the presence of numerous macrophages. Capeans et al. (Retina. 1998;18(6):546-50) reported that monocyte chemotactic protein-1 (MCP-1) present at significantly higher levels in the vitreous of eyes with vitreoretinal disorders than the vitreous of control eyes, and hypothesized that MCP-1 may be involved in the recruitment of macrophages and monocytes into the vitreous of eyes with proliferative vitreoretinal disorders. Other groups have reported that macrophages are activated in rabbits during the inflammatory phase of the development of proliferative vitreoretinopathy (PVR). Hui et al. Graefes Arch Clin Exp Ophthalmol. 1999 July, 237(7): 601-5; Chen et al. Ocul Immunol Inflamm. Mar. 10, 2002 (1): 27-39; Martin et al. Ophthalmic Res. 2003 July-August, 35(4): 232-8.
Other immune mechanisms have also been implicated in ARMD. For example, auto-antibodies with specificity for retinal tissue have been detected in ocular pathologies, including ARMD (Penfold et al. Graefes Arch Clin Exp Ophthalmol. 1985 223:69-76). C-reactive protein, a serum protein associated with inflammation, is elevated in subjects with ARMD. (Seddon et al. (2004) JAMA 291:704-10) At the tissue level, confirmation of inflammatory cell infiltrates has been documented for early, intermediate, and late stage disease. (Penfold et al. (1985) Graefes Arch Clin Exp Ophthalmol. 223:69-76) Immunohistochemical analysis of drusen has demonstrated the presence of immunologic antigens, to include complement components C5, C5b-9, immunoglobulin, and HLA-DR. (Russell et al. (2000) Am J Ophthalmol. 129:205-14) For a review of the immunological and etiological aspects of macular degeneration, see Penfold et al. (2001) Retinal Eye Res 20:382-414.
More recently, the role of macrophages in ARMD has been examined using transgenic mice deficient for either monocyte chemoattractant protein (MCP-1), or its cognate chemokine receptor, CCR-2. (Ambati et al. (2003) Nat Med. 9:1390-7). These transgenic animals developed ARMD abnormalities that include the characteristic display of RPE drusen, accumulation of lipofuscin, photoreceptor atrophy, and CNV. Ambati et al. hypothesized that impaired macrophage recruitment may allow accumulation of C5a and IgG, which induces vascular endothelial growth factor (VEGF) production by RPE, possibly mediating development of CNV.
Diagnosis and prognosis of ARMD has primarily focused on assessing drusen (e.g., total drusen area or the size of drusen), which has been identified as the most important conventional risk factors for ARMD progression (Latkany (2004) medscape.com/viewarticle/494566). Other conventional techniques in screening and diagnosis include fluorescence angiography (FA), optical coherence tomography (OCT), spectral OCT, and scanning laser ophthalmoscope with OCT (SLO-OCT). Therapies for ARMD are largely in the experimental stage and focus on treatment of wet ARMD. Exemplary therapies include those directed toward inhibition of neovascularization such as laser photocoagulation, photodynamic therapy (which may be accompanied by administration of a light-activated drug such as VISUDYNE®), transpupillary thermotherapy, microcurrent stimulation, and administration of antiangiogenic agents, radiation therapy, and surgery. A review of convention therapies is provided by Lois et al. (2004) Comp Ophthalmol Update 5:143-161.
There is a need for methods of indicating development and/or progression of these ocular diseases such as ARMD, and for treatment of such diseases. The present invention addresses these needs.
Additional Literature
Ocular Diseases, Including ARMD
Additional literature which may be of interest relating to ocular diseases, and particularly ARMD, includes: Penfold et al. (1987) Graefes Arch Clin Exp Ophthalmol 225:70-6; Killingsworth et al. (1990) Eye 4:613-621; Nishimura et al. (1990) Ophthalmologica 200:39-44; Weller et al. (1991) Exp Eye Res. 53(2):275-81); Otani et al. (1999) Invest Ophthalmol Vis Sci 40:1912-1920; Grossniklaus et al. (2000) Mol Vis 8:119-26; Spandau et al. (2000) Invest Ophthalmol Vis Sci 41:S836; Van der Schaft et al. (2001) Invest Ophthalmol Vis Sci 33:3493; Grossiklaus et al. (2002) Mol. Vis 8:119-226.
Macrophayes
Macrophages are terminally differentiated cells generally incapable of further cell division. Macrophage proliferation has been implicated in certain serious proliferative diseases such as lymphoma, cardiovascular disease, and nephrosclerosis. U.S. Pat. No. 5,639,600. Gabrielian et al. reported the role of macrophage infiltration in traumatic proliferative vitreoretinopathy. ((1994) Curr. Eye. Res. 13: 1-9). McGrath et al. disclosed the involvement of clonally expanded macrophages in the induction of cancerous tumor growth and AIDS dementia. U.S. Pat. Nos. 5,639,600 and 5,580,715; see also Pulliam et al. (1997) Lancet 349:692-695; McGrath et al. (1995) J. Acquired Imm. Def Syn. Hum. Retro. 8: 379-385; Shiramizu et al. (1994) Cancer Res. 54:2069-2072.
Polyamine Analogs and Anti-proliferative Activity
Certain anionic oligomers have antiproliferative activity. In particular water soluble polyureas and polyamides with a molecular weight of less than 10,000 inhibit smooth muscle cell proliferation in culture and in vivo, and have been suggested for treatment of atherosclerosis (U.S. Pat. No. 5,460,807; see also U.S. Pat. No. 5,516,807 (relating to use of bis-ethyl norspermine in vascular proliferative disorders)). Certain triazoles are antiproliferatives; in particular amino 1, 2, 3 triazoles inhibit labeled thymidine incorporation into intact pig skin, inhibit keratinocyte proliferation, and have been suggested for use in treatment of psoriasis, a chronic skin disease characterized by epidermal hyperproliferation (U.S. Pat. No. 4,847,257). Derivatives of valproic acid decrease neuro-2a cell proliferation in vitro, and have been suggested for use in prevention and treatment of neurodegenerative disorders such as Alzheimer's disease to inhibit pathologic neural cell growth (U.S. Pat. No. 5,672,746).
The level of polyamines is intimately related to cell proliferation. Cellular levels of polyamines are carefully regulated by opposing synthetic and catabolic pathways. Compounds that are able to lower polyamine levels are proposed for use in the treatment of rapidly proliferating host cells such as cancer and psoriasis. A key polyamine catabolizing enzyme spermidine-spermine N1-acetyltransferase (SSAT) is among the few genes known to be inducible by the natural polyamines. Certain polyamine analogs exaggerate this response. 1,11-diethylnorspermine (DENSPM) increases SSAT mRNA levels in human melanoma cells up to 20-fold, with an increase in immunodetectable SSAT protein by 300-fold. By comparison, natural polyamine spermine is far less effective, increasing SSAT mRNA by ˜3-fold and immunodetectable protein by ˜7-fold. Fogel-Petrovic et al.(1996) Biochemistry 35:14435. Polyamine analogs also induce Z-DNA structure in vitro. This property correlates inversely with the effects on cis-diaminedichloroplatinum (II) (CDDP) cytotoxicity in human brain tumor cells. Basu et al. (1996) Anticancer Res. 16:39.
U.S. Pat. No. 5,498,522 outlines the use of SSAT, or other determinants related to SSAT induction such as SSAT co-factor acetylCoA, and the SSAT products N1-acetylspermine and N1-acetylspermidine, as a prognostic indicator or tumor response marker. Measurement of these determinants is proposed as a prognostic indicia and tumor response marker to evaluate the clinical effectiveness of anticancer agents comprising polyamine analogs. Hibasami et al. [(1989) Cancer Res. 49:2065] prepared methylglyoxal-bis(cyclopentylamidinohydrazone) (MGBCP) as an inhibitor of the natural polyamine synthetic pathway. MGBCP inhibits S-adenosylmethionine decarboxylase, spermine synthase, and spermine synthetase, competing with S-adenosylmethionine, spermidine, and putrescine, respectively. MGBCP depleted spermidine and spermine in leukemic ascites cells, and prolonged survival time of mice bearing P388 leukemia.
U.S. Pat. No. 5,541,230 (Basu et al.) indicates that spermine derivatives decrease growth in a number of human tumor cell lines, and propose their use in cancer chemotherapy. Bergeron et al. (Cancer Chemother. Pharmacol.) showed that the polyamine analogs 1,14-bis(ethylamino)-5,10-diazatetradecaone (BE-4-4-4), and 1,19-bis(ethylamino)-5,10,15-triazanonadecane (BE-4-4-4-4; see U.S. Pat. No. 5,541,230)) directly affects growth, survival, and cell cycle progression in human brain tumor cell lines. For other publications relating to the synthesis and use of certain polyamines, the reader is referred to EP 277,635, EP 162,413, EP 399,519, JP 85/6348, and U.S. Pat. No. 5,679,682; and to Bellevue et al. (1996) Bioorg. Med. Chem. Lett. 6:2765, and Porter et al. (1992) Falk Symposium 62:201; Marton and Pegg (1995) Ann Rev. Pharmacol. Toxicol. 35:55-91.